Tag Archive for: drought

How Current Drought Compares to 2011

The Texas Water Development Board (TWDB) recently produced a fascinating short video that puts the current drought in historical perspective by comparing rainfall, temperature, and water supplies to 2011. The text and visuals below are adapted from Dr. Mark Wentzel’s presentation. Wentzel serves as a hydrologist for the TWDB.

Wentzel’s charts depict statewide averages. The Houston region has had significantly more rainfall. So look at Wentzel’s data for trends happening around us. I’ll show Houston data at the end of this post.

Comparison to 2011 Drought

Wentzel says that June was warmer and drier than normal for much of the state, the fourth consecutive month with those conditions. At the end of June, drought conditions covered 86 percent of the state, up eight percentage points from the end of May. Storage in our water supply reservoirs is at 75 percent of capacity, ten percentage points below normal for this time of year. So, Texas is in a significant drought, the worst since 2011, but not worse than 2011.

Highlights of Wentzel video

Statewide Precipitation Averages

The State average rainfall from January to June of this year: 7.8 inches, about 60 percent of normal. Bad as that may be, it’s better than in 2011 when we received less than six inches in the first half of the year, only about 40 percent of normal.

Statewide Texas precipitation averages

Comparison to 2011 Temperatures

On the next chart, Wentzel shows monthly average temperatures across the entire state for both 2022 in orange and 2011 in red. Black dots show the 20th century average for comparison. He shows maximum and minimum temperature records in gray. The gold line represents January to June of this year.

Statewide Texas temperature averages

Temperatures have been above average five out of six months. That additional heat has certainly contributed to drought, but monthly temperatures in the first half of 2011 were even hotter for four of those six months.

In 2011, the real heat came in June, July, and August when we set maximum temperature records each month.

Dr. Mark Wentzel, TWDB

Temperatures the rest of the summer and 2022 are expected to be warmer than average, but not to exceed 2011 temperatures.

Percent of State in Drought

Low rainfall and high temperatures during the first half of 2022 have brought significant drought to Texas. The U.S. Drought Monitor map for conditions as of June 28 shows 86 percent of the state impacted by drought, up eight percentage points from the end of May. More of the state is experiencing drought at the end of June this year than for any June since 2011, when 96 percent of the state was in drought.

Effect on Water Supply

Statewide, our water supply reservoirs are being impacted by the current drought, but not as significantly as in 2011. The dark line on this chart shows how storage this year compares to minimum, maximum, and median values for the day of the year from data going back to 1990. Lighter lines show how we did in 2021 and 2020. The red line shows how we did in 2011.

Texas statewide totals expressed as percent of full capacity

We began 2022 with water supply storage more than two percentage points lower than normal for the time of year. By the end of June, we’ve fallen to about ten percentage points lower than normal.

In 2011, water supply began the year closer to normal, but fell farther and faster than in 2022. By the end of June, storage was about one and a half percentage points less than this year. In the second half of 2022, Wentzel expects additional storage declines, but not as severe as in 2011 when the State reached 30-year lows by mid-October.

Bottom Line for State

We are in a significant drought, even if it’s not as bad as 2011. But the real test won’t come this summer or even this year. Our water supply systems are designed to withstand a multi-year event. Will 2022 lead to a multi-year event? It’s too early to tell, says Wentzel. “But it’s never too early to conserve water and manage demand.”

Houston

The charts below comes from the National Weather Service Climate site and depicts conditions at Bush Intercontinental Airport.

The top half of the first shows temperatures. It depicts highs in red, average ranges in green, and lows in light blue for ever day of the year. The dark blue lines show actual temperature observations year to date.

The bottom half shows actual precipitation compared to the average. You can see that for part of the year, we were actually above normal. But starting around June 1, we fell behind.

The last chart shows temperatures in July to date. The dark blue lines show actual temps compared to highs, the normal range, and lows for every date. The three stars indicate records or ties.

Posted by Bob Rehak on 7/15/22 based on information from TWDB, NWS and Dr. Mark Wentzel

1781 Days since Hurricane Harvey

Why Worry about Flooding in a Drought?

This morning, Harris County Meteorologist Jeff Lindner sent me an email that caused me to worry. It wasn’t about flooding. It was about our dismal rain chances for the next two weeks.

His email also contained a map of all the outdoor burn bans in effect across the state. Of 254 counties in Texas, 133 currently ban burns.

According to the Texas A&M Forest Service, more than half of Texas counties have burn bans in effect.

Texas’ drought monitor website shows that as of 6/15/22:

  • 91.4% of the state is abnormally dry.
  • 80% is in moderate drought.
  • 64% is in severe drought.
  • 42.5% is in extreme drought.
  • 16.8% is in exceptional drought.
  • Drought affects 19.3 million people in Texas.
  • We’ve had the 8th driest year to date in the last 128 years.

So why worry about flooding now? Here are my top three reasons. You may have others.

Repetitive Cycles

Previously, Lindner sent a separate email comparing 2022 with 2011, the start of our last major drought. Within it, he said, “While it is easy to compare heat and drought to other instances in the past, our current heat and drought is far from what this region and state went through in 2011. Rainfall has been much more plentiful this spring than in 2011, and while some of the temperatures may be similar, the intensity of the heat thus far this year is not to the level of 2011. There are some similar comparisons to drought and heat of the summers of 1998, 1988, and 1980.”

The drought years caught my eye. I asked him if there was a reason for the relative regularity.

He replied, “Generally speaking … a lot of our heat/drought and floods correlate with El Niño and La Niña in the central and eastern Pacific. La Niña years tend to favor heat and drought in the southern plains, though not always. 2011 was one of the strongest La Niñas on record since 1950. On the other hand, El Niño tends to favor cooler and wetter periods. Many of our big floods have happened in El Nino years.”

Knowing that floods follow droughts in regular cycles (and that floods could happen at any time from a stray tropical storm), you never want to be lulled into a false sense of security about flooding.

Complacency

Droughts can create complacency about flooding. People forget the pain. Political pressure and attention shift to more pressing problems, such as crime or Covid. And after two years of lockdown, people are ready for vacation, even with $5/gallon gasoline! But like the parable of the Three Little Pigs, people who live in SE Texas can never become complacent about flood threats. Flooding is our #1 natural disaster.

After Harvey, flooding floated to the top of Houstonians’ concerns. We launched massive mitigation efforts. But do you know where they stand today?

Apathy when we’re not flooding could sow the seeds of the next big flood. Vigilance is the price of freedom…from flooding, too.

Unintended Consequences

Most research on hydrological risks focuses either on flood risk or drought risk. However, floods and droughts are two extremes of the same hydrological cycle. They are inextricably linked. One follows the other like night follows day.

Strategies targeted at one may create unintended consequences for the other. So, it is important to consider interactions between these closely linked phenomena.

For instance, drought can decrease groundwater, kill ground cover, and increase erosion. Erosion can create sediment dams that contribute to flooding. We knew giant sand bars like the one below were likely to form in the headwaters of Lake Houston since the 1990s. But our mayors at the time refused to dredge. Even though there was no imminent threat, that turned out to be a costly decision.

The West Fork San Jacinto mouth bar in the headwaters of Lake Houston in 2018. Before/after measurements show that as much as ten feet was deposited in this area during Harvey (five below water/five above). This and other bars have since been dredged, but the Army Corps said they blocked the river 90%.

I could list more examples. But you get the idea. Even though another Harvey is not lingering offshore at the moment, how much have we really learned? How much have actually improved conditions that increased flood risk during Harvey?

Please stay in the fight to make our homes, businesses and community safer.

Posted by Bob Rehak on 5/17/22

1753 Days since Hurricane Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

NWS Says Chance of San Jacinto River Flooding in Next Three Months is Minor

The National Weather Service (NWS) predicts only minor flood risk for both the West and East Forks of the San Jacinto through the end of May. That’s the good news.

NWS predicts only minor long range flood risk for the East (38.85%) and West Forks (26.22%) of the San Jacinto.

Drought Conditions Expanding Across Texas

But there is a downside: potential drought.

The reason for the low risk has to do with a below-average rainfall pattern across much of Texas. The Texas Water Development board posted two stories in the Texas Water Newsroom last week about the potential for drought. Large parts of the state are already severely behind on rainfall for the year and the pattern is expected to continue through May when weakening La Niña conditions could return us to normal.

Source: Texas Water Development Board as of end of February 2021.

The map above shows that most of the Houston area has received about 90% of expected rainfall year to date. But large parts of the state have received less than 20%. TWDB predicts those dark areas on the map will expand at least through May. At that point, TWDB predicts only the extreme eastern part of the state will not be in some kind of drought condition.

At the end of February, drought covered just over half the state, according to the TWDB. Statewide storage in our water-supply reservoirs is at 82 percent of capacity, about three and a half percentage points less than normal for this time of year. 

Drought Relief Could Come as La Niña Fades

Says Dr. Mark Wentzel, Texas Water Development Board Hydrologist, “The National Weather Service anticipates drought expansion across all but the eastern edge of the state by the end of May. Looking a little farther out there is some good news. La Niña conditions, that are at least partially responsible for drought in Texas, are expected to dissipate after April.”

So, the river flooding outlook could be very different by Hurricane season this year.

Did snow in February not help? Not really. Wentzel points out that snow is mostly air. It takes up to a foot of snow to equal and inch of rain.

Posted by Bob Rehak on 3/14/2021

1293 Days since Hurricane Harvey

Friday Flood Digest

Here’s a digest of recent flood-related happenings. Follow the links for more detailed information.

Texas’ First-Ever Regional Flood Planning Process Gets Underway

The Texas Water Development Board (TWDB) is helping recently formed regional-flood planning groups deliver 15 regional flood plans by January of 2023. These regional flood plans will form Texas’ first-ever state flood plan, due to the legislature by September of 2024.

The Board designated flood-planning group members on October 1st. The regional flood planning group meetings are publicly posted under the Texas Open Meetings Act. The first meetings were posted on the TWDB website and the Secretary of State website. Groups have two objectives:

  • Reduce current flood risk
  • Prevent creation of new flood risk 

Flood Projects Move Closer to Funding

Flood projects eligible for funding through the State’s Flood Infrastructure Fund (FIF) moved one step closer to becoming a reality this week. Select applicants are currently submitting complete (as opposed to abridged) project applications to the TWDB. These applications will help Texas communities finance drainage and flood mitigation and control projects.

Eligible entities submitted 280 abridged applications for more than $2.3 billion in financial assistance.

TWDB culled that list to fit the available $770 million in funding for structural and nonstructural flood projects. Of that $770 million, TWDB will allocate $231 million (30 percent) to grants and $539 million (70 percent) to loans with no interest.

TWDB Chairman Peter Lake characterized this program as one of the biggest steps the State has ever taken toward flood mitigation.

As of November 5, 2020, the TWDB had received 125 applications from cities, counties, water districts, and other political subdivisions. The deadline for full applications is November 23.

Four of five SJRA abridged applications made the cut:

  • Upper San Jacinto Sedimentation Study
  • Spring Creek Flood Control Dams Conceptual Engineering Study
  • Lake Conroe/Lake Houston Joint Operations Study
  • Flood Early Warning System for San Jacinto County

Chuck Gilman, SJRA’s Director of Water Resources and Flood Management, said, “We hope to receive final notice on our four full applications in late December or early January.”

“The causes and effects of flooding vary from region to region, so there is no single ‘silver bullet’ solution to mitigate floods,” said Lake. “It is critical that we support Texas communities as they plan for and mitigate future risks based on their unique needs and circumstances.”

The Board will consider approving financial assistance commitments at public meetings in the coming months.“Financial assistance will help communities with both flood planning and project implementation. While we can’t avoid natural disasters, we can mitigate the damage they do,” said Lake.

Fire and Flooding

Fire and flooding may seem like a strange combination. But yes, fire can contribute to flooding. I first noticed this phenomenon on an island called Guanaja in the Bay of Honduras where I used to scuba dive. One year, poachers set fires at the bottom of a hill to drive exotic tropical birds toward nets at the top of the hill. The next year, half the hill slid into the Caribbean during heavy rains.

So what does that have to do with Houston? As drought approaches, developers continue to set fires to clear land. That kills all the grasses that retain soil. When rain does return, that soil will wash downstream and likely contribute to the mouth bar growing on the San Jacinto East Fork. Reduction of the river’s “conveyance” can back water up and contribute to flooding.

Drought Vs. Flooding

Jeff Lindner, Harris County Meteorologist says, “The focus for the last several years has been on flooding and heavy rainfall. We’ve had floods in some portion of Texas for each of the last 5 years. However, the onset of moderate to strong La Niña conditions in the Pacific appear to be swinging the state back toward a dry period.”

“What was predicted to be an active period next week is slowly decreasing both “cold” and “moisture” wise in recent model runs, as is typical in La Nina winters,” says Lindner.

Climate Prediction Center outlooks for the next two weeks indicate below average rainfall and above average temperatures. Similar outlooks continue for three months. Vegetation health will continue to decline, but likely at a slower rate than during the hot summer months when heat is maximized.  

Three month outlook from NOAA predicts below average rainfall across southern US.

So be careful of outdoor burning (see story above). Many counties have already imposed outdoor burn bans.

Note outdoor burn ban in Liberty County.

The only positive side of drought is that it can make ideal construction weather for flood-mitigation projects (see two stories above).

Harris County Community Flood Resilience Task Force Has First Meeting

The Harris County Community Flood Resilience Task Force held its first meeting earlier this month. The first order of business: expand the group’s membership from five to 17. The group is creating a web site which will accept online applications; it should be up shortly.

The application deadline: December 11. Stay alert for more information if you are interested in representing your area. Preference will be given to those:

  • Who have flooded
  • Represent flood-prone communities
  • Have knowledge in certain areas, such as housing, public health, engineering/construction, urban design/planning, flood-risk mitigation, environment, etc.

Water Baron of Montgomery County Takes On World; Lawyers Drool

Simon Sequeira, CEO of Quadvest and the Water Baron of Montgomery County, continues his War with the World. At the last GMA14 meeting, lawyers are reportedly lining up to get a piece of the action and licking their lips.

Sequeira also supplies water to Colony Ridge in Liberty County. Several years ago, he led a fight to get the board of the Lone Star Groundwater Conservation District elected rather than appointed. Then he backed candidates who favored unlimited groundwater pumping and promised to Restore Affordable Water.

Broken Promises

While groundwater is cheaper than surface water, water bills reportedly failed to come down. However, he has stopped paying the SJRA. Sequeira says he is setting aside that money in a special fund in case he loses his legal battle with the SJRA. But his legal battles go far beyond the SJRA. He’s also taking on the rest of GMA14.

GMA14 includes the 15 colored counties above, each represented by a different conservation district. Montgomery County (dark blue) has the Lonestar Groundwater Conservation District.
Purpose of Groundwater Management Areas

GMA stands for groundwater management area. GMAs were set up years ago, in part, to make sure that one county doesn’t hog groundwater, depriving surrounding areas and creating subsidence. So the other counties in GMA14 get to approve (or not) the groundwater withdrawal rates in Montgomery County.

They do that by defining “desired future conditions.” How much drawdown in an aquifer is acceptable? How much subsidence can people and infrastructure tolerate?

GMA14 wants Sequeira to leave 70% of the water in aquifers intact and to produce no more than 1 foot of subsidence.

Hired-Gun Experts Defy Scientific Consensus

Ever since, Sequeira took on this fight, his hired-gun experts have been trying to prove subsidence doesn’t pose a threat in Montgomery County. Unfortunately, data and models don’t agree with him. His pumping has already created subsidence in MoCo and now threatens northern Harris County, too.

Strangely enough, while science has shown – and the rest of the world believes – that unlimited groundwater pumping causes subsidence, Sequeira does not. His profit margin depends on cheap groundwater, unfettered by fees designed to encourage people to convert to surface water.

Five Alternative Plans Considered

Sequeira and company originally proposed three alternative plans to GMA14 that involved pumping:

  • 900 feet of decline in the Jasper Aquifer
  • 700 feet of decline in the Jasper Aquifer
  • 250 feet of decline in the Jasper Aquifer (Similar to Run D scenario, modeled below.)

Of those three, GMA14 only considered the last (even though Lone Star and GMA14 use different criteria to describe the volume pumped).

GMA14 countered by adding two more alternatives that involved even less pumping:

  • 115,000 acre-feet per year (Similar to Lone Star’s Run D scenario. See below).
  • 97,000 acre-feet per year
  • 61,000 acre-feet per year

The two sides are still arguing about how much can be pumped safely. And that’s why the lawyers are drooling.

Models Show Unacceptable Subsidence from Sequeira’s Least Damaging Plan

Subsidence can alter the landscape in ways that cause water to collect in areas that otherwise might not flood. The maps below model projected subsidence in south Montgomery and northern Harris Counties. And we know that this model under-predicts subsidence. That’s because it doesn’t model ANY subsidence from the Jasper aquifer.

Sequeira’s least damaging plan would cause up to 3.25 feet of subsidence in southern Montgomery County and up to 3 feet in northern Harris County, according to GMA14. See below.

Pumping 115,000 feet per year would cause up to 3.25 feet of subsidence in southern MoCo.
The same amount of pumping would cause up 3 feet of subsidence in parts of Kingwood and Huffman, and a foot or more in much of the rest of Harris County.
Effect on Humble, Kingwood, Atascocita, Huffman Areas

If you live in the Lake Houston Area and you stare at that last subsidence map long enough, eventually you will come to a jaw-dropping realization. The Lake Houston spillway is only subsiding by a foot. But the headwaters of the lake are subsiding up to 3 feet. Imagine filling your bathtub with water and then tilting it two feet.

Homes and businesses in the headwaters of Lake Houston will be lowered 2 feet relative to the spillway.

That’s a huge amount. Those who built homes a foot above the hundred year flood-plain would find themselves a foot below it. Those who had a couple inches of water in their homes would have more than two feet after subsidence.

Battle Lines Drawn

So the battle lines are drawn. Sequeira wants to allow up to 900 feet of decline in the Jasper aquifer. And GMA14 wants no more than 1 foot of subsidence with 70% of the aquifer intact. That would mean pumping less than 100,000 acre feet per year.

The presence of so many lawyers in the last GMA14 meeting reportedly has the smaller groundwater management districts nervous. One observer used the word “intimidated.” Some don’t have financial resources to fight Sequeira.

Lawyers I talk to believe Sequeira has little chance of winning a lawsuit. But who needs a favorable judgment when you have an army of lawyers that can intimidate the other side into backing down.

However, if Sequeira is successful, he could open up himself and the Lone Star Groundwater Conservation District to billions of dollars in “takings” claims. The lawyers make out coming and going.

Posted by Bob Rehak on 11/20/2020

1179 Days since Hurricane Harvey

The thoughts expressed in this post represent opinions on matters of public concern and safety. They are protected by the First Amendment of the US Constitution and the Anti-SLAPP Statute of the Great State of Texas.

From Drought to Floods: The Decade in Review

Jeff Lindner, the Harris County Flood Control District Meteorologist compiled this Decade in Review. After a very dry start, the decade ended incredibly wet. We started with five years of below normal rainfall (2010-2014). Then rains and floods returned in 2015 and continued through 2019. For the period from 2010-2014, the rainfall DEFICIT for BUSH IAH was -56.70 inches. For the period from 2015-2019, the rainfall SURPLUS was +69.78 inches.

Five Deficit Years…

2010: 42.72 (-7.07)

2011: 24.57 (-25.2)

2012: 43.32 (-7.45)

2013: 38.84 (-10.93)

2014: 43.72 (-6.05)

Followed by Five Surplus Years

2015: 70.03 (+20.26)

2016: 60.96 (+11.19)

2017: 79.69 (+29.92)

2018: 56.02 (+6.25)

2019: 51.93 (+2.16)

The decade featured one of the most significant droughts since the 1950’s across the state of Texas and a series of floods that rivals any period of flooding ever experienced in this state.

Jeff Lindner, Harris County Flood Control Meteorologist

1. Hurricane Harvey (2017)

Harvey made landfall at Port Aransas on August 27, 2017 at 10:00 pm as a category 4 hurricane with 130mph winds producing extensive wind damage across portions of the Texas coastal bend. A maximum wind gust of 132mph was recorded at Port Aransas and 118mph at Copano Bay. Harvey would then meander slowly east-northeast across portions of southeast Texas and the extreme northwest Gulf of Mexico producing record breaking rainfall and flooding.

A maximum total rainfall of 60.58 inches was recorded at Nederland, TX with over 10,000 square miles receiving over 35 inches of rainfall.

Across Harris County, on average 33.7 inches of rainfall occurred, resulting in record flooding along many of the bayous and creeks. In additional inflows into Addicks and Barker Reservoirs resulted in record pool elevations (exceeded Tax Day by 6.0 feet) in both reservoirs and significant flooding of structures located within the flood pools. Water flowed around the north end spillway of Addicks for the first time since the completion of the dams in the 1940’s.  In Harris County alone over 154,000 homes were flooded and statewide over 250,000 homes were damaged from either flooding or wind. An estimated 500,000 vehicles were damaged or destroyed.

In the counties of Jefferson, Orange, Hardin, and Tyler upwards of 110,000 structures were flooded which is about 33% of the total number of structures in these four counties.

The highway 96 bridge over Village Creek near Silsbee, TX was completely washed away. In Fort Bend County over 200,000 residents were asked to evacuate due to flooding from Barker Reservoir, the Brazos River, and local drainage issues with some 8,700 homes being flooded. Over 9,000 homes were flooded in Brazoria County and over 7,000 in Galveston County. Many of the creeks, bayous, and rivers in southeast Texas surpassed previously held flood records by several feet.

More than 100,000 residents were rescued across southeast Texas by both government and civilian resources with more than 40,000 sheltered in over 150 shelters.

Over 336,000 customers lost power during the hurricane mainly across the coastal bend from wind related damages, but also in the Houston and Beaumont areas from flooding.

Harvey resulted in 125 billion dollars in damage making the hurricane the second costliest hurricane in American history (behind Katrina 2005). Harvey is the worst flooding event to ever impact the United States and resulted in the highest death toll from a landfalling tropical system in the state of Texas since 1919 with over 68 direct fatalities (36 in Harris County alone).

2. Drought/Wildfires (2011)

One of the worst droughts to impact the state of Texas and southeast Texas occurred in 2011 resulting in widespread mandatory water restrictions, the loss of millions of trees, and significant wildfires. High temperatures during the drought were some of the warmest on record and exceeded the extreme heat of the summer of 1980.

For the period from February 1 to August 18, Hobby Airport only recorded 6.36 inches of rainfall breaking the previous driest record from those dates by 6.25 inches. On August 27, 2011, Houston IAH reached a high temperature of 109 at 2:44pm which tied the hottest all-time temperature from September 4, 2000 for the city of Houston.

Over the Labor Day weekend of 2011, primed vegetation from the drought combined with strong winds of 30-40mph on the western side of Tropical Storm Lee over Louisiana produced one of the most devastating wildfire events in Texas history. The Bastrop fire burned over 35,000 acres and some 1600 homes and is the single most devastating wildfire in Texas history.

The tri-county fire (Waller, Grimes, Montgomery Counties) burned over 19,000 acres and some 100 homes. In September 2011, the statewide PDSI index fell to -7.97 or its lowest values ever, indicating the 2011 drought was nearly as equal in severity as the drought of record in the 1950’s.

For 2011, Tomball averaged a rainfall deficit of over 40 inches. Overall statewide water storage fell to 58.78% at the end of October 2011 and Lake Conroe fell to -8.0 feet below its conservation pool. Lake Travis fell to -54.61 feet below its conservation pool or (34% capacity). 644 jurisdictions across the state were under mandatory water restrictions.

The City of Houston also recorded 47 days above 100 degrees (previous record was 32 in 1980). Huntsville recorded 72 days above 100 (previous record was 43 in 1980). The incredible heat of August 2011 was estimated to be a 10,000 year return event for the City of Houston.

3. Tropical Storm Imelda (2019)

Tropical Storm Imelda formed 15 miles off the coast of Brazoria County and made landfall near Freeport on September 17, 2019. Imelda would slowly drift north-northeast across SE TX during the 18th and into the 19th.

Early on the morning of the 19th an extensive band of heavy thunderstorms producing extreme amounts of rainfall developed from Jefferson County to east-central Montgomery County.

Rainfall rates under this band frequently exceeded 4.0-5.0 inches per hours with a few locations receiving over 6.0 inches per hour.

This band of excessive rainfall drifted south-southwest in Harris County by mid morning. 31.0 inches of rainfall was recorded in just 12 hours at Fannett, TX near the Chambers/Jefferson County line with a storm total of 44.29 inches of rainfall at that site.

The 44.29 inches recorded at Fannett, TX makes TS Imelda the 4th wettest tropical cyclone in Texas history and the 5th wettest in US history dating back to 1851.

A 48-hour rainfall total of 29.1 inches was recorded in northeast Harris County near Huffman with 30.4 inches recorded in southeast Montgomery County near Plum Grove. 6.5 inches of rain fell in just 1 hour over the Aldine area of Harris County.

The resultant flooding in Jefferson, Liberty, Chambers, and portions of northeast and north central Harris County equaled and in some cases exceeded that of Harvey.

While overall storm total rainfall amounts were less than Harvey, the duration (intensity) at which some of the rainfall occurred in certain areas was much greater for Imelda than for Harvey yielding in certain instances areas that would flood in Imelda and not Harvey. 3,990 homes flooded in Harris County alone. Several thousand flooded in Montgomery, Liberty, Chambers, and Jefferson Counties.   

4. Tax Day Flood (2016)

On April 17-18, 2016 a slow moving to at times stationary cluster of thunderstorms producing excessive rainfall rates developed over portions of Waller, Austin, northern Fort Bend and western Harris County. Over the next 12 hours rainfall amounts of 12-24 inches would occur from southern Waller County into portions of western Harris County resulting in extensive and severe flooding.

The flooding resulted in 9 fatalities in Harris, Waller, and Austin Counties (7 in Harris County) with an estimated 40,000 vehicles flooded and 9,840 homes flooded in Harris County alone.

A maximum 14.5 hour rainfall rate of 23.50 inches was recorded in Pattison in southern Waller County with 19.30 inches occurring at Monaville in 10 hours.

Modern day record flooding occurred along Cypress Creek and in portions of Addicks Reservoir (only to be exceeded a year later by Harvey).

Significant flooding occurred along the lower Brazos River, only to be exceeded a month later when 20 inches of rainfall fell near Brenham, TX. Addicks Reservoir peaked at its highest level ever recorded at 102.65 feet (only to be exceed by Harvey the following year).

5. Memorial Weekend (2015)

Devastating flooding impacted the state of Texas over the Memorial Day weekend in 2015. The initial onslaught began with excessive rainfall and resulting catastrophic flooding along the Blanco River at Wimberley where the river rose over 30 ft in less than 3 hours. It reached a peak elevation of around 40.2 ft (flood stage 13ft) and exceeded the previous record of 33.3 ft (an 86 year old record).

The Blanco River at San Marcos rose 17 ft in 30 minutes and over 29 ft in 2.5 hours.

Over 1000 residents were displaced and over 350 homes in Wimberley destroyed and washed away. The storm killed 13 persons including 8 from a single river house that washed away. The Ranch Road 165 and Fischer Store Rd bridges across the river were completely destroyed and the Ranch Road 12 bridge sustained significant damage.

The following day, a line of intense thunderstorms would originate in central Texas and move into southeast Texas and slow over southwest Harris County. A total of 8.0 inches of rainfall would fall in a 3 hour period.

11.0 inches fell in 12 hours north of US 59 and Beltway 8 resulting in extensive flash flooding. The first ever Flash Flood Emergency was issued for Harris County at 10:52pm. There were 7 fatalities in Harris County (4 from submerged vehicles at underpasses).

Statewide a total of 27 people died in flash flooding. Flooding along Brays and Keegans Bayous was the most extensive since September 1983 and along Buffalo Bayou since March 1992 and TS Allison (2001).

A total of 6,335 homes flooded in Harris County and an additional 3,540 multi-family units flooded. Some of the same homes would be flooded a year later with the “Tax Day Flood” and all would flood again during Harvey 2 years later. 

That’s the decade in review! If you weren’t browning, you were drowning. Any time your friends and family in other states start complaining about the weather there, send a link to this page to them.

Posted by Bob Rehak on 12/31/2019

854 Days since Hurricane Harvey and 103 since Imelda

NY Times Article Says Quarter of Humanity Facing Looming Water Crisis

An article in the New York Times about a looming water crisis caught my eye today. Datelined Bangalore, India, the article describes how “Countries that are home to one-fourth of Earth’s population face an increasingly urgent risk: The prospect of running out of water.” So what does that have to do with flooding? Many of those countries also experience cyclic flooding. Sound familiar?

Uncanny Parallels to Houston

In yet another uncanny parallel to our situation – i.e., with the Water Wars in Montgomery County – “…some are squandering what water they have. Several are relying too heavily on groundwater, which instead they should be replenishing and saving for times of drought.”

And then we have the subsidence parallel. Mexico City, claim the authors, draws groundwater so fast that the city is literally sinking.

In Chennai, India’s fourth largest city, residents accustomed to relying on groundwater for years now find none left. So the city is forced to transport water from farther and farther away (like our Luce Bayou Project). They lose significant amounts in the process due to evaporation and leakage.

The World Resources Institute expects the number of people worldwide living in “extremely high water stress” to nearly double in the next decade.

Cape Town, a city roughly the size of Houston, had to ration water last year.

Drought and Flooding Solutions Often Overlap

In Bangalore, lakes that once dotted the city have been filled in, much the way we fill in wetlands, so they can no longer collect rainwater and serve as the city’s water storage tanks.

That parallel reminded me of the dwindling water capacity in Lake Houston due to sedimentation. With backup supplies in Lake Livingston and Lake Conroe, Houston certainly doesn’t have to worry about running out of water any time soon. But as recent sedimentation surveys near the mouth bar showed, we do have to worry about loss of lake capacity.

Difference map developed by Tetra Tech for City of Houston in Feb/March, 2019, showing areas of deposition and scour near the West Fork Mouth Bar. Overall, Tetra Tech estimates that this small 350-acre area of Lake Houston gained 504-acre feet of sediment since the previous survey in 2011. Brown areas represent more than 5 FEET of deposition.

Drought and floods represent two sides of the same coin. This article reminded me that solutions to one problem can also help solve the other. For instance…

  • Developing adequate surface water supplies and saving ground water as the backup. This can reduce subsidence which can lead to flooding.
  • Improving lake/river capacity by dredging can eliminate blockages that also cause flooding.

As we move forward with West Fork and maintenance dredging, we should remember this. We aren’t just looking at costs that benefit Lake Houston residents. We’re looking at costs that benefit millions of residents in the larger metropolitan area. It’s not just about flooding. It’s also about water capacity for a rapidly growing population.

Posted by Bob Rehak on 8/6/2019

707 Days since Hurricane Harvey